(A) Application parameters
PARAMETERS
535
5
GROUP
A
Selection of restart operation (Pr.162)
NOTE
• Because a DC injection brake is applied instantaneously at speed detection during a restart, the speed might drop if the
moment of inertia (J) of the load is small.
• Restart operation with reduced voltage is not available for PM sensorless vector control.
Restart coasting time (Pr.57)
• The coasting time is the time up till detection of the motor speed and start of restart control.
• To enable restart operation, set "0" (no coasting time) in Pr.57 Restart coasting time. Generally, this setting does not
interfere with inverter operation.
• Inverter operation is sometimes hindered by the size of the moment of inertia (J) of the load or running frequency. Adjust
this coasting time within the range 0.1 s to 30 s to match the load specification.
Adjustment of restart operation (Pr.611)
• Using Pr.611, the acceleration time to reach Pr.20 Acceleration/deceleration reference frequency after a restart
operation can be set. This can be set individually from the normal acceleration time.
NOTE
• Changing the Pr.21 Acceleration/deceleration time increments setting does not affect the Pr.611 setting increment.
• An IPM motor is a motor with interior permanent magnets. Regression voltage is generated when the motor coasts at an
instantaneous power failure or at a flying start. The inverter's DC bus voltage rises if the motor coasts fast or makes a flying
start in this condition.
When using the automatic restart after instantaneous power failure function (Pr.57 "9999"), it is recommended to also use
the regenerative avoidance function (Pr.882 Regeneration avoidance operation selection = "1") to make startups stable. If
the overvoltage protective function (E.OV[]) still occurs with the regeneration avoidance function, also use the retry function
(Pr.67).
• During PM sensorless vector control, the automatic restart after instantaneous power failure function operates only when an
MM-CF IPM motor is connected
When a built-in brake or a regeneration unit is used, the frequency search may not be available at 2200 r/min or higher.
The restart operation cannot be performed until the motor speed drops to a frequency where the frequency search is
available.
• At a power restoration, the encoder detects the motor speed by a
frequency search so that the inverter can re-start smoothly.
• The encoder also detects the rotation direction so that the inverter
can re-start smoothly even during the reverse rotation.
• When "10 (11, 12, 13)" is set in Pr.162, a restart operation is
performed at each start and automatic restart after instantaneous
power failure. When "0 (1, 2)" is set to Pr.162, a restart operation is
performed at the first start after a power-ON, and from the second
power-ON onwards, a start from the starting frequency is performed.
Caution
An IPM motor is a motor with interior permanent magnets. High voltage is generated at motor
terminals while the motor is running.
Do not touch motor terminals and other parts until the motor stops to prevent an electric shock.
When the automatic restart after instantaneous power failure function is selected, the motor
suddenly starts (after reset time passes) when an instantaneous power failure occurs.
Stay away from the motor and machinery.
Apply the supplied CAUTION stickers to easily visible places when automatic restart after
instantaneous power failure has been selected.
Instantaneous (power failure) time
Power supply
(R/L1,S/L2,T/L3)
Motor
speed N (r/min)
Inverter output
frequency f (Hz)
Inverter output
voltage E (V)
Coasting
time (Pr.57)
Speed
detection
time
+
Acceleration time
at a restart
(Pr.611 setting)
* The output shut off timing differs
according to the load condition
*
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